sources: factor out 'Fetch source data' box into view component.

app/components/source_data_component.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+class SourceDataComponent < ApplicationComponent
+  attr_reader :source
+  delegate :spinner_icon, to: :helpers
+
+  def initialize(source:)
+    @source = source
+  end
+end